1. Field of the Invention
The present invention relates, generally, to mineral classification systems and, more particularly, to sluice boxes for wet placer mining. Further along these same lines, the sluice box of the present invention is particularly adapted for portable mobility in order that the same may be transported with relative ease to remote locations for wet placer mining of mineral-containing detrital material or placer ground.
2. Description of the Background Art
Wet placer mining is of course historically well known. It has been employed, literally for centuries, in the classification or separation of minerals from detritus, both alluvial and glacial, the classification being conducted on the basis of density separation. Conventionally, a sluice box is utilized for initial concentration of these mineral-containing materials by separation of coarser rock and lighter sand constituents. Routinely, the concentrated deposits then undergo further classification; e.g., they are "panned" to obtain valuable minerals. Gold, platinum, and like elements have been mined in this way for quite some time.
A wide range of designs for sluice boxes useful in wet placer mining has been proposed over the years. The usual design includes a trough or the like for receiving a charge of placer earth which is moved along a path under the influence of water. Sometimes the trough includes a separating or classifying table or plate which allows smaller pieces of rock, sand, along with the minerals, to fall to a lower lever while moving the larger rocks and similar constituents along the materials path. It is also sometimes helpful to incorporate transversely spaced riffles which provide flow impediments to the finer materials passing through the separation plate; allowing sand and similarly less dense material to travel somewhat more freely through the sluice than the heavier mineral particulate which tends to be trapped along the upstream edges of these elements. It is also sometimes advantageous to utilize a coarse mat which lies beneath the riffles to trap the minerals; which mat may then be removed with the mineral particulate intact for transferring the concentrated deposit to a secondary recovery device. A customary secondary recovery technique is hand panning, whereupon the mineral elements may be recovered.
The patent art presents an interesting patchwork of sluice boxes. Ranging from U.S. Pat. No. 516 (issued Apr. 23, 1831) which disclosed a so-called ore washer having a perforate classification table to U.S. Pat. No. 4,199,441 which concerns a high volume sluice box having multiple separation stages, the art has evolved substantially. Riffle-like members have been incorporated within inclined troughs, provided by folds in a sluice blanket; the same component thereby functioning for two different elements as disclosed in U.S. Pat. No. 73,160. U.S. Pat. Nos. 1,588,102 and 1,752,169 are noteworthy for disclosure of mineral concentrators or separators which include wire screens and perforated metal components for gravity separation of the constituents constituting a charge of mineral-bearing material; optionally including a layer of burlap or Brussels carpet to trap the finer and denser minerals. Along these latter lines, cf., e.g., U.S. Pat. Nos. 157,192 and 386,030. Rather unique separation plate constructions are the subject of U.S. Pat. No. 1,725,765, where a metal sheet is pierced in a desired pattern and portions thereof bent downwardly in the form of tabs or "lips" which cooperate with riffles in the device.
Although the art is conceptually well developed, modern needs and interests are not well accommodated by the old approaches. For several reasons, wet placer mining is most efficiently conducted in backcountry. On the one hand, more accessible sources of valuable detritus have been mined extensively and most have played out. On the other hand, many individuals relish the opportunity to engage in this type of activity more in the nature of a hobby to be coordinated with other outdoor enjoyments. In any of these events, however, the sluice box necessary for placer mining in this fashion must be transported to remote regions; entailing the need to carry the device over many miles and usually through harsh terrain. Sluice boxes known in the art are simply not adapted to those needs. Most sluice boxes tend to be large and unwieldy. They are much too heavy and large to be carried, let alone conveniently. Simply reducing size in order to reduce thereby the problems attendant lack of portable mobility is not an efficient answer; that ad hoc approach usually results in a device totally inefficient for its intended purpose of mineral classification.
Accordingly, the need exits to provide an improved sluice box which possesses portable mobility, allowing it to be transported with relative ease to remote regions, but without sacrificing separatory efficiency. The present invention responds to such needs.